Seasonal Affective Disorder affects millions internationally, all winter long. Caused by a biochemical imbalance in the hypothalamus, and sometimes vitamin D deficiency, it is curable—with the right treatments at the right time.
Symptoms include sleep problems, fatigue, overeating, especially a craving for carbohydrates , sweet foods. Changes in insulin levels, a depressed mood, minimal social contact and decreased interest in sex all can be part.
Vitamin D status affects a person’s mood. In a double-blind study of healthy students (mean age, 22 years), supplementation with vitamin D (400 or 800 IU per day) in combination with vitamin A for five days during the winter resulted in significantly improved mood. Vitamin A by itself was no help. Not surprisingly, the UK has a leg up on treatment, and an excellent site on symptoms.
Risk factors for vitamin D deficiency include residing above 35 degrees latitude, avoiding sun exposure, having dark skin, being obese or elderly. The most reliable laboratory test for vitamin D status is the serum concentration of 25-hydroxyvitamin D. Vitamin D3 (the type of vitamin D sold over the counter and produced in the skin) is safer than vitamin D2.